1. Technical Field
The present document relates to electronic circuits. In particular, the present document relates to dynamic level shifter circuits utilizing coupling capacitances and cross coupled latches.
2. Background
It is common that some power management systems use independent power voltage domains. Voltages in such power domains may not be related to each other and careful level shifting strategy is required. Level shifters are converting an input signal e.g. from a first operating voltage range having a first ground potential and a first supply potential into an output signal out in a second operating voltage range having a second ground potential and a second supply potential. For example input VDD (regulated to 5V) can be regulated by an LDO that is supplied (connected) to Vpwr voltage. And Vpwr can be directly connected to the unregulated battery voltage (one/two/three cell battery voltages) for example with specification of 4.2-12.6V if connected together. VSS2 can be also regulated, for example (Vpwr-5V). During operation as battery voltage (Vpwr) decay VSS2 can approach regulated VDD or it can be below VDD if VDD is supplied externally. Conventional level shifters may stop operation under such conditions.
It is a challenge for the designers of level shifters to overcome the drawbacks cited above.